Electronic counter



Sept. 16, 1958 J. B. woLFlNG-roN ELECTRONIC COUNTER Filed Dec. l1, 1956 INVENTOR Jeffery Wo/'ngfon A TTO/QA/E Vf ELECTRONC CUNTER Jeery B. Wellington, Palo Alto, Calif., assigner to Hewlett-Packard Company, Palo Alto, Calif., a corporation of California Application December 11, 1956, Serial No. 627,686

1t) Claims. (Cl. 235-92) This invention relates generally to electronic counters and more particularly to electronic counters capable of relatively high counting rates.

It is a general object of the present invention to provide a counter capable of high counting rates.

It is another object of the present invention to provide a counter capable of high counting rates and which includes a beam switching tube.

It is another object of the present invention to provide a counter including a beam switching tube which gives a staircase read-out voltage.

lt is still another object of the present invention to provide a counter employing a beam switching tube which includes a neon lamp read-out.

It is another object of the present invention to provide an electronic counter which includes a beam switching tube and which gives a staircase read-out voltage whose level is maintained about a given reference potential.

These and other objects of the invention will appear more clearly from the following description and attached drawing which is a circuit diagram of the decade counter of the present invention.

Referring to the drawing, the counter includes a beam switching tube 11, schematically illustrated. In actual construction the beam switching tube comprises a high vacuum tube which has a centrally located cathode 12 surrounded by identical arrays. Each array is composed of a plate or target 13, a grid (switching grid) 14, and a beam forming and locking element (spade) 16. A small cylindrical permanent magnet is mounted outside the tube envelope and serves to direct the electron beam.

In normal operation, the electron beam is formed between the central cathode and one of the arrays or positions. The beam can ow to' only one of the positions at any one time. The greatest portion of the beam current flows to the respective plate where it provides a useful output to operate a neon lamp or other indicating device, as will be presently described. rthe associated spade draws enough beam current to maintain it slightly below the cathode potential and thus to lock the beam on a particular target. The beam may be made to remain indenitely in any one position or may be advanced from position to position, the direction of advance being determined by the polarity of the magnetic iield. The position at which the beam is formed is generally referred to as the on position. The adjacent electrode group to which the beam normally advances is called the lead position. The beam is switched from the on position to the lead position by applying a large negative pulse to the on grid. This pulse frees the on target of the electron beam and allows the magnetic iield to rotate the beam. The beam then impinges upon a highly positive spade which conducts and rapidly falls to approximately cathode potential, thus forming and locking the electron beam on the next target. rEhis target now becomes the on target. The count is advanced.

'2,852,194 Patented Sept. 16, 1958 To re-set the tube to zero, a large negative pulse is supplied to all spades simultaneously. This extinguishes the electron beam. The beam is reformed at the zero position by applying a larger pulse on the zero spade than that applied to the other spades. The beam is formed and locked on the zero target.

Beam switching tubes of this type are well-known and may, for example, comprise a beam switching tube of the type manufactured by Haydu Brothers of New Jersey, Subsidiary of Burroughs Corporation.

A resistive attenuator network 17, to be presently described in detail, is connected to the plates or targets of the beam switching tube. The output from the attenuator is a staircase read-out voltage and is available at the line 1S. Neon lamps 19 provide a visual read-out. Each of the lamps 19 are connected to one of the plates and to the line 21 which is connected to the common terminal of the resistors 22 and 23. The resistor 23 has one side grounded. The resistor 22 is connected to the plus voltage supply through the resistor 24 and is connected to ground through the capacitor 26.

The staircase read-out voltage on the line 18 has its levels maintained around a given reference potential by the staircase regulator 32.

The signal to be counted is fed through a pulse amplifier 27 to the grids 14 of the beam switching tube. Reset pulses are applied to the reset amplifier 2S. A single output pulse for every ten input pulses is obtained at the nine target or plate and amplied by the amplifier 29. The pulse is available at the line 31.

The attenuator 17 comprises serially connected resistors 33-42. Resistors tft- 3 connect the targets to points along the serially connected resistors. The line 1S is connected to ground through the resistor 56. Voltage is supplied from the +V supply to the attenuator network and the plates through the resistor 24. The resistive network forms a ladder attenuator. The targets are capacitively coupled to ground by the capacitors 57-66. The attenuator network 17 serves to supply a read-out voltage along the line 18 which is of the staircase type with each step of the staircase corrresponding to a particular on position.-

As previously described, the staircase output levels are maintained about a given reference potential by the staircase regulator tube 32.. The tube 32; has its cathode grounded. The grid is connected to the cathode through the capacitor 71. The grid is also connected to the cathode 12 of the beam switching tube which in turn is connected to the V supply through the parallel combination of resistors 72 and '73. The plate of the tube 70 connects to the +V supply line through the resistor 74. The plate is also connected to the resistors 7o-85 which are in the beam switching tube spade circuit.

The amplier 29 includes the tube 87 which has its grid resistively capacitively connected to the nine target. The network comprises serially connected resistors 89a, 89h, 89e and 89d. Capacitor 9i! is shunted across resistor 89a. Capacitors 91a and 91h are connected between the terminals of resistor 89C and ground. The grid is also conected to the V supply through the resistor 88. The action of the ampliiier and coupling network is to differentiate and amplify the positive going pulse which occurs at the nine target when the beam switches from the nine target to the Zero target. The plate of the tube is connected to the +V supply through the plate resis tor 92.

The reset pulse is applied to the grid 93 of the tube 94. The cathode of the tube is connected to ground through a parallel network comprising resistor 96 and capacitor 97. The plate is capacitively connected to the resistor 76 through the capacitor 98. The common terminal of the resistor 76 and capacitor 98 is connected to the resistor 77 by the parallel combination of resistor 99 and capacitor 101.

The input pulse is fed to the grid 102 of the tube 103. The suppressor grid is connected to the cathode which is grounded. The screen grid is connected to the plate. The plate of the tube 103 is connected to the switching grids through the serially connected capacitor 104 and inductor 106. The plate is connectedto the plus voltage supply through the resistor 107 and inductor 108 which are serially connected.

The switching grids of the beam switching tube 11 are connected to the line 109 through the network which comprises the diode 111 connected in parallel with the resistor 112 which combination is serially connected to the capacitor 113 which is connected in parallel with a portion of the tap resistor 114. The other portion of the resistor 114 is serially connected with the two parallel combinations. The complete combination is connected between the grids and the line 109.

Operation of the apparatus is as follows: In a normal counting sequence, the beam switching tube is first reset to zero by application of an external pulse to the grid 93 of the reset amplifier 28. The amplifier output is' a highly negative which is a few microseconds wide and which is applied to all of the spades of the beam switching tube, thus extinguishing the electron beam. After the negative pulse, the spades are returned to their normal potential and the beam reforms on the zero position since the negative pulse is maintained longer on the zero spades than on the other spades by the action of the resistivecapacitive network associated therewith.

The signal to be counted is then fed to the `grid 102 of the input pulse amplifier 27. The output pulses from the amplilier pass through the series parallel combination of peaking coils 108 and 106 which, together with the associated circuitry, provide a negative pulse to all the grids of the switching tube. The peaking coils serve to form a negative pulse which has a short pulse width and large amplitude. This is essential to insure single step sequential switching.

With each pulse applied to the input pulse amplifier, the beam advances to the next lead position. A single output pulse `for every ten input pulses is provided at` the line 31. The output pulse can then be used to drive another decade counter unit or a similar device. The pulse is obtained by differentiating and amplifying the positive going pulse which occurs at the nine target when the beam switching tube switches from the nine to the zero target.

As the count advances7 the attenuator circuit 17 serves to provide a voltage at the lead 18 which is a staircase voltage, each of the steps representing a particular count. The regulator 32 serves to maintain the output levels of the staircase voltage around a given reference voltage.

Apparatus was constructed in accordance with the foregoing and as illustrated. The components had the following values:

56 l0megohms.

76-83 100 ktleach.

8S 240kn.

89a 240 kn.

96 100ktz.

Capacitors:

57-66 22 ,unf each.

100 Mrt 91a 47 Maf 91h 47 auf 97 5000 ,unf

104 270 auf Inductors:

Diode: 111 Known by manufacturers specitication as CR 101.

Voltages:

-V -llS v.

Apparatus constructed with the foregoing constants was tested and was capable of counting rates of 1 mc. and higher. A staircase voltage which varied between 53 and 137 volts with each step equal to 9.3 4volts was obtained.

Thus it is seen that an improved electronic counter is provided. The `counter is capable of relatively high counting rates and provides a staircase output voltage. means are provided for giving a visual read-out` I claim: v

l. A counter comprising a beam switching tube having a central cathode surrounded by a plurality of arrays each comprising plate, grid and beam forming elements, a resistive network connected to said plates and serving to provide a staircase readout voltage, regulating means connected to said resistive network and serving to regulate the staircase voltage, and means for applying switching pulses to said grid elements and serving to switch the beam from one plate -to another in response to input pulses.

2. Apparatus as in claim l including a pulse amplifier adapted to receive and amplify input pulses, said amplitier serving to supply sharp pulses to the grid elements of the beam switching tube.

3. Apparatus as in claim 2 wherein said amplier includes inductive peaking means.

4. Apparatus as in claim 1 wherein said resistive network comprises a plurality of serially connected resistors with a plurality of resistors each connected between the junctions of the serially connected resistors and a respective plate of the array.

5. A counter comprising a beam switching tube having a cathode and a plurality of arrays each including plate, grid and beam forming elements, a resistive network connected to said plates and serving t-o provide a staircase read-out voltage, regulating means connected to said resistive network and serving to regulate the staircase voltage, reset means serving to reset the tube to zero in response to a reset pulse, and means forming an output pulse every ten input pulses.

6. Apparatus as in claim 5 including a pulse amplifier adapted to receive and amplify input pulses, said amplifier serving to supply sharp pulses to the grid elements of the beam switching tube.

7. Apparatus as in claim 6 wherein said amplifier includes series parallel peaking coils in the plate circuit.

8. Apparatus as in claim 7 wherein said resistive network comprises series and parallel resistors with the parallel resistors connected by the plates.

9. A counter comprising a beam switching tube having a cathode and a plurality of arrays each including plate, grid and beam forming electrodes, a resistive network connected to the said plates and serving to provide a staircase read-out voltage, regulating means connected to said resistive network and serving to regulate the staircase voltage, neon lamps associated with each plate and serving to provide a visual read-out, and means for applying switching pulses to said grid elements and serving to switch the beam from one plate to another in response to input pulses.

10. Apparatus as in claim 9 wherein said resistive network comprises a plurality of serially connected resistors with a plurality of resistors connected in parallel between the junctions of the serially connected resistors and the plates.

References Cited in the le of this patent UNITED STATES PATENTS 2,427,533 Overbeek Sept. 16, 1947 2,432,608 Desch et al. Dec. 16, 1947 2,599,949 Skellett June 10, 1952 2,670,405 Mohr Feb..23, 1954 2,677,074 Reuter Apr. 27, 1954 2,772,390 Woodruff Nov. 27, 1956 

